Lowe AL, Abou-Saleh MT. The British experience of dual diagnosis in the national health service. The co-occurrence of substance misuse and other psychiatric disorder (dual diagnosis) has been increasingly recognized in the UK. Clinical studies of patients with severe mental disorders showed high rates of substance misuse with poor clinical and social outcome. These patients often fall ‘between the cracks’ of the separate general psychiatric and addiction services. This has necessitated the development of a national policy advocating the provision of integrated care within mainstream psychiatric services. There are emergent models of good practice that require evaluation of effectiveness and cost effectiveness.